Alloy for use as a pot or container for molten light metals



Patented Mar. 27, 1951 UNITED STATES PATENT OFFICE ALLOY FOR USE AS A POT OR CONTAINER FOR MOLTEN LIGHT METALS Claude M. Sheridan, New Kensington, and Theodore A. Pruger, Creighton, Pa., assignors to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation of Pennsylvania N Drawing. Application January 12, 1950, Serial No. 138,272

Claims.

etc. must have special properties if they are to be successfully employed in handling such metals. Pots for this purpose have heretofore had a relatively short period of life. Such light metals in a molten state normally tend to pass through a nickel bearing heat resistant box, thus an alloy is needed that will be resistant to penetration and damage by the light metals being handled. Oxidation resistance is needed to prevent spalling; heretofore, it has been necessary to periodically spray a protective coating on the pots for this purpose. We have determined that an alloy used for this purpose must have a superior oxidation resistance, if it is to have a reasonable period of useful life.

It has thus been an object of our invention to provide an alloy having superior oxidation resistance which may be employed in providing pots for molten light metals;

Another object has been to provide a workable alloy which has a good corrosion resistance to molten magnesium, a superior oxidation resistance, and will hold its scale after being heated and cooled.

In accordance with our invention, we have provided an alloy that is relatively inexpensive, that has a better refined grain structure, and that has an increased corrosion resistance. It has superior oxidation resistance to about 1800 F. and thus fully fills the need for containers, boxes or pots of the type here involved. The alloy may be made within the following composition:

C, .08 to .15% Cr, 9 to 12% Mn, 19 to 24% Si, 1 to 2% Zr, .5 to 1% Somewhat wider ranges may be employed while retaining oxidation resistance and other good characteristics, as indicated from the following composition:

C, up to .25% max. Cr, 8 to 15% Mn, 19 to 24% Si, 1 to 2.5% Zr, .5 to 2% Remainder substantially all iron with incidental impurities.

An optimum alloy contains:

C, .08 to .15%

Cr, 10 to 12% (best about 10%) Mn, 19 to 20% (best about 20%) Si, 1.5 to 2% (best about 2%) Zr, .5 to 1% In the alloy of our invention, the silicon and zirconium are particularly critical in their proportioning. Rolling difficulties are encountered if the zirconium istoo high and also too much silicon would be required, producing an unbalanced composition. Phosphorus and silicon may be present in normal amounts as incidental impurities.

Heretofore it has been believed that zirconium did not convey any valuable properties to an alloy of the type here involved and had a tendency to increase melting difiiculties and unsoundness. We have discovered that a proper proportioning of the silicon and zirconium provides maximum corrosion resistance. Although zirconium normally has poor solubility and difficulty is encountered in obtaining its uniform distribution in a melt, resulting in a low yield of about 10 to 20%, we have overcome this difiiculty by adding zirconium and for optimum results, ferro zirconium silicon, in a ferrous metal container or box to a melt or bath of the principal metal alloying elements. A rod is attached to the container for inserting the latter into the melt. We use a relatively thin-walled ferrous metal (steel) can or enclosed container that will melt in the bath and which does not have to be hermetically sealed. After the principal metal elements have been melted down, the slag is scraped off the surface of the melt and the container is then introduced and held under the surface of the molten metal until the container melts off the rod. At this time, the zirconium attains a full diffusion through the melt. The container permits the zirconium to be heated up before it enters the melt and in addition, the ferrous metal, itself, appears to further aid the diffusion of the zirconium. In this Way, we obtain a 40 to 45% yield and a fully uniform distribution (full diffusion) of the zirconium, eliminating segregation, improving the workability of the alloy, etc.

What we claim is:

1. An improved chromium-manganese alloy which contains up to about .25% maximum carbon, about 8 to 15% chromium, about 19 to 24% manganese, about 1 to 2.5% silicon, about .5 to 2% zirconium, and the remainder substantially 1 3 iron with incidental impurities, the alloy being characterized by its superior oxidation resistance.

2. An alloy as defined in claim 1 wherein, the zirconium is fully dissolved within and uniformly distributed throughoutit.

3. An improved chromium-manganese alloy which contains up to about .25% maximum carbon, about 8 to 15% chromium, about 19 to 24% manganese, about 1 to 2.5% silicon, and about .5 to 2% zirconium in a fully diffused state therein as effected by introducing it directl and underneath the surface of a melt made up of the above specified principal metal alloying elements, and the remainder substantially iron with incidental impurities, the alloy being characterized by its superior oxidation resistance.

4. An improved chromium-manganese alloy which contains up to about .25% carbon, about 8 to 15% chromium, about 19 to 24% manganese, about 1 to 2.5% silicon, about .5 to 2% zirconium, and the remainder iron with incidental impurities, the alloy being characterized by its superior oxidation resistance.

5. An improved chromium-manganese alloy which contains about .08 to .15% carbon, about 9 to 12% chromium, about 19 to 24% manganese, about 1 to 2% silicon, about .5 to 1 zirconium, and the remainder substantially iron with incidental impurities, the alloy being characterized by its superior oxidation resistance.

6. An alloy as defined in claim having the additional characteristic of good workability and whose superior oxidation resistance is retained up to 1800 F.

'7. An improved chromium-manganese alloy which contains about .08 ,to .15% carbon, about 9 to 12% chromium, about 19 to 24% manganese, about 1 to 2% silicon, about .5 to 1% zirconium, and the remainder iron with incidental impurities, the alloy being characterized by its superior oxidation resistance. 7

8. An improved chromium-manganese alloy 4 which contains about .08 to .15% carbon, about 10 to 12% chromium, about 19 to 20% manganese, about 1.5 to 2% silicon, and about .5 to 1% zirconium, and the remainder substantiall iron with incidental impurities, the alloy being characteriz'ed by its superior oxidation resistance.

9. An improved chromium-manganese alloy which contains about .08 to .15% carbon, about 10% chromium, about 20% manganese, about 2% silicon, about .5 to 1% zirconium in a fully diffused state therein, and the remainder substantially iron with incidental impurities, the alloy being characterized by its superior oxidation resistance.

10. An improved chromium-manganese alloy which contains, about .08 to .15% carbon, about to 12% chromium, about 19 to 20% manganese, about 1.5 to 2% silicon, about .5 to 1% zirconium, and the remainder iron with incidental impurities, the alloy being characterized by its superior oxidation resistance.

CLAUDE M. SHERIDAN. THEODORE A. PRUGER.

REFERENCES CITED The following references are of record, in the file of this patent:

UNITED STATES PATENTS Number Name Date 887,648 Kemery May 12, 1908 2,190,486 Sohafmeister 1 Feb. 13, 1940 2,283,299 Tisdale May 19, 1942 FOREIGN PATENTS Number Country Date 595,404 Great Britain Dec. 4, 1937 OTHER REFERENCES Metals Handbook, 1948 edition, pages 327 and 328. Published in 1948 by the American Society for Metals, Cleveland, Ohio. 

1. AN IMPROVED CHROMIUM-MANGANESE ALLOY WHICH CONTAINS UP TO ABOUT .25% MAXIMUM CARBON, ABOUT 8 TO 15% SILICON, ABOUT .5 TO MANGANESE, ABOUT 1 TO 2.5% SILICON, ABOUT .5 TO 2% ZIRCONIUM , AND THE REMAINDER SUBSTANTIALLY IRON WITH INCIDENTAL IMPURITIES, THE ALLOY BEING CHARACTERIZED BY ITS SUPERIOR OXIDATION RESISTANCE. 